7mm Allen Magnum/RL33/180 gr Berger testing

[mark fox]

Carbon build up is a problem with all super overbore plazma cutter cartrages. It can be a real problem with the 6.5's. Keeping clean is a must. Most of my rounds being berger are seated .007 off and at the top end of preasures limits seems to be the norm for berger and accuracy. Have you ever used rl 50 powder several burn charts show it between h 870 and 50 bmg. I saw some yeasterday I think i will give it and us 869 a try. Strange how just a little change can make so much diffrence. I use to use lots of retembo. I still have 25 plus pounds but only use it in one cartrage. and most of the cartrages I use to use it in I now use magpro with better velocity accuracy and less felt recoil . I use magpro in my 25-284 ai, 6.5-284 ai, 6mm s.o.b br (bore right) 6.5 taz, 7stw ai b.r. (bore right) If you havent used it try it in place of retembo. Its a super performance GOD sent powder form above.

 

[rooster721]

Mark (and) fifty -both...

What barrel twist are you guys using in your 7mm's to get those bullets to hold together at that velocity?

Kirby, you & I have discussed the Bergers some in the past, however I've still got trouble with them in an 8" twist 5R.. obviously have to barrel a slower twist next time. Just curious how much slower* Neither the Matrix or Berger Target Hybrids hold together in mine. Both turn to smoke-puffs every-other round. Am stuck shooting solids the remainder of this particular barrels-life, unless the 195 shoots alryt in it.. only time will tell THAT though

 

[mark fox]

rooster 721.


is the 721 in your name for the remington 721 ? To awnser your question. in the 7mm 1-8 5 lands super match form pacnor have had no problems with even the thin skin vld hunting some guys use 1-8.5 some use 1-8 3 lands. As far as the 6.5's 1-8 5 lands s/m pacnor. I have pushed the 140 gr vld 3800 fps for years in several guns aprox 10,000 rounds and dont think i have had one ever come apart. In fact I did some testing berger wanted to know how fast the 6.5 could be pushed before it came apart. I did foward ignited duplex stacked powder load on a closed bolt face schultz & larsen m60 4 lug rear locking nickle action shot 20 rounds between 3898 and 3945 w/ 140 grain berger vld only 2 came apart that gun now has head spacing issues and the bolt is no longer smooth in the action. So with that somthing is wrong with your barrel. use a pacnor barrel. I have built over 500 rifles with pacnor and had only one problem. out of true center on a chrome molly it shot 3/4 moa indexed it was replaced for free

 

[Fiftydriver]

Carbon build up is a problem with all super overbore plazma cutter cartrages. It can be a real problem with the 6.5's. Keeping clean is a must. Most of my rounds being berger are seated .007 off and at the top end of preasures limits seems to be the norm for berger and accuracy. Have you ever used rl 50 powder several burn charts show it between h 870 and 50 bmg. I saw some yeasterday I think i will give it and us 869 a try. Strange how just a little change can make so much diffrence. I use to use lots of retembo. I still have 25 plus pounds but only use it in one cartrage. and most of the cartrages I use to use it in I now use magpro with better velocity accuracy and less felt recoil . I use magpro in my 25-284 ai, 6.5-284 ai, 6mm s.o.b br (bore right) 6.5 taz, 7stw ai b.r. (bore right) If you havent used it try it in place of retembo. Its a super performance GOD sent powder form above.

I have used Magpro a lot and do like it in cartridges that are a bit limited in capacity. In my testing of RL50, its burn rate is very similar to H-50 BMG but its MUCH denser so you can get significantly more powder in the same powder capacity space so normally you will get more velocity but can not say its much different in burn rate. Good powder.

In your 7mm, I suspect it will be a bit to bulky still.

 

[Fiftydriver]

Mark (and) fifty -both...

What barrel twist are you guys using in your 7mm's to get those bullets to hold together at that velocity?

Kirby, you & I have discussed the Bergers some in the past, however I've still got trouble with them in an 8" twist 5R.. obviously have to barrel a slower twist next time. Just curious how much slower* Neither the Matrix or Berger Target Hybrids hold together in mine. Both turn to smoke-puffs every-other round. Am stuck shooting solids the remainder of this particular barrels-life, unless the 195 shoots alryt in it.. only time will tell THAT though

I use 1-9 on all my 7mm. Never had a problem. Do not like the 3 groove for thin jackets bullets. To much baring surface compression and can have bullet failure once barrels get some wear on them. Standard 6 groove or 5R work best for me.

In my opinion, you have more RPMs then needed depending on your velocity.

 

[rooster721]

rooster 721.


is the 721 in your name for the remington 721 ? To awnser your question. in the 7mm 1-8 5 lands super match form pacnor have had no problems with even the thin skin vld hunting some guys use 1-8.5 some use 1-8 3 lands. As far as the 6.5's 1-8 5 lands s/m pacnor. I have pushed the 140 gr vld 3800 fps for years in several guns aprox 10,000 rounds and dont think i have had one ever come apart. In fact I did some testing berger wanted to know how fast the 6.5 could be pushed before it came apart. I did foward ignited duplex stacked powder load on a closed bolt face schultz & larsen m60 4 lug rear locking nickle action shot 20 rounds between 3898 and 3945 w/ 140 grain berger vld only 2 came apart that gun now has head spacing issues and the bolt is no longer smooth in the action. So with that somthing is wrong with your barrel. use a pacnor barrel. I have built over 500 rifles with pacnor and had only one problem. out of true center on a chrome molly it shot 3/4 moa indexed it was replaced for free

721 in my handle refers to 7.21 Firebird actually, and is also the caliber my twist-rate question is tied to..

I've had the 190 matrix and 180 Berger's both up to 3300fps without over-pressuring in mine, the wall I hit had everything to do with the jackets tearing and bullets bursting 30/40 yards outta the muzzle. Including the "supposed" thicker-jacket Target Hybrids. I've since shelved hopes to shoot either bullet. Even backing-off charges and velocities down as low as 3000 hasn't solved my jacket-issue.. As Kirby says, (and I-too have come to lean this way) I have to believe they're just being over-spun and coming apart... the part that makes a guy scratch his head is your comment about (your-own) 8-twists shooting even "hunting" vld's okay.. obviously I'll take your word, but gotta wonder how it could be.

I will mention, this particular barrel isn't the only barrel it's happened. I've seen it in 2 barrels now.. one worn-out 9-twist, badly roughened toward the end of it's life (and) this "once" bran-new 8-twist, only the roughened up part is irrelevent to this-one. It's not roughend at all (which is why I attributed the jacket-problem to the twist)

So not sure what the real answer will be next-time I rebarrel. Maybe split the difference and go 8.5" (?) ...I don't know-- would like to try the 195's in-it yet, to see if indeed 1:8 is the way to go (for them) or if an 8.5-twist would do, then leave the option open to fall back to the 180's if neccesary down the road. Tough call to make which barrel actually will be the ticket... having a non-mainstream caliber has perks but-also has it's negatives. Guy ends up "pioneering" data for the **** things, lol.. really very little to go by with them

 

[mark fox]

its not the caliber or the velocityor even the bullets its your barrel. I would get a new one. no need to have the 1-8 get the 1-8.5 that will stablize the 195 bergers

 

[mark fox]

velocity is not the problem look at the 7stw many people shoot them at 3000 fps 7mm ultra mag 3000 fps. Its your barrel. get 1-8.5 6 lands super match and you will have no problems and stablize the 195's when they come out.

 

[Kiwi Greg]

its not the caliber or the velocityor even the bullets its your barrel. I would get a new one. no need to have the 1-8 get the 1-8.5 that will stablize the 195 bergers

When will the 195 Bergers be available ? that's the 27 cent question.....

 

[mark fox]

I should be getting some soon for testing. I am on there test list & have tested other bullets for them. But to awnser your question they say june or perhaps july 2015

 

[Fiftydriver]

721 in my handle refers to 7.21 Firebird actually, and is also the caliber my twist-rate question is tied to..

I've had the 190 matrix and 180 Berger's both up to 3300fps without over-pressuring in mine, the wall I hit had everything to do with the jackets tearing and bullets bursting 30/40 yards outta the muzzle. Including the "supposed" thicker-jacket Target Hybrids. I've since shelved hopes to shoot either bullet. Even backing-off charges and velocities down as low as 3000 hasn't solved my jacket-issue.. As Kirby says, (and I-too have come to lean this way) I have to believe they're just being over-spun and coming apart... the part that makes a guy scratch his head is your comment about (your-own) 8-twists shooting even "hunting" vld's okay.. obviously I'll take your word, but gotta wonder how it could be.

I will mention, this particular barrel isn't the only barrel it's happened. I've seen it in 2 barrels now.. one worn-out 9-twist, badly roughened toward the end of it's life (and) this "once" bran-new 8-twist, only the roughened up part is irrelevent to this-one. It's not roughend at all (which is why I attributed the jacket-problem to the twist)

So not sure what the real answer will be next-time I rebarrel. Maybe split the difference and go 8.5" (?) ...I don't know-- would like to try the 195's in-it yet, to see if indeed 1:8 is the way to go (for them) or if an 8.5-twist would do, then leave the option open to fall back to the 180's if neccesary down the road. Tough call to make which barrel actually will be the ticket... having a non-mainstream caliber has perks but-also has it's negatives. Guy ends up "pioneering" data for the **** things, lol.. really very little to go by with them

At your velocity level, there is no need for anything faster then a 1-9 twist. That said, when you get to this level of velocity, just as important as twist rate is the percentage of baring surface compression on the jacket by the rifling. You want this to be less then 20% of the total surface of the bullets contact with the bore. If its higher then this, you will have bullets come apart as the barrel gets a bit of wear on it.

I have tested the HECK out of this when I started with my 7mm Allen Magnum. 3 groove barrels are generally no good as they have very wide lands that compress to much of the jacket and weaken the bond between the jacket and core. Standard 6 groove rifling often does very well. I have NEVER had a problem with a Lilja 6 groove 1-9 twist even up to the 200 gr ULD RBBT wildcat bullets we used to be able to use and I can tell you it will work on anything lighter as well.

I have seen problems with the matrix bullets when they are driven to speeds that your talking no matter what twist rate your using. That said, I have never had a berger 180 gr hybrid target bullet have any problems at all even up to 3500 fps in a 1-9 6 groove Lilja or 1-9 5R from Bartlein.

Again, your problem may be as much baring surface compression as it is twist rate.

Can be confusing to figure out to begin with.

 

[Fiftydriver]

When will the 195 Bergers be available ? that's the 27 cent question.....

They are coming, can not offer any details on this but trust me, they are coming!!!

 

[mark fox]

kirby is correct about 1-9 and the velocity stablized and the bearing surface the faster you go the less you need. depending on the bullet design. i use the 180 hybrid in my 284 tyrannos but still dont have any problems with vld hunting as of yet.